A study showed that from the early 1990s to 2005, the proportion of stroke victims under the age of 55 in one region of the United States rose from 13 per cent to 19 per cent.
The average age at which people experienced a first stroke also fell, from 71 to 69. The Stroke Association described the research as “alarming”.
Lead researcher Dr Brett Kissela, from the University of Cincinnati College of Medicine in Ohio, said: “The reasons for this trend could be a rise in risk factors such as diabetes, obesity and high cholesterol.”
The findings are published in the latest online issue of the journal Neurology.